In-situ injection of potassium hydroxide into briquetted wheat straw and meadow grass – Effect on biomethane production

Abstract Alkaline pretreatment of lignocellulosic biomass has been intensively investigated but heavy water usage and environmental pollution from wastewater limits its industrial application. This study presents a pretreatment technique by in-situ injection of potassium hydroxide concentrations ranging from 0.8% to 10% (w/w) into the briquetting process of wheat straw and meadow grass. Results show that the biomethane yield and hydrolysis rate was improved significantly with a higher impact on wheat straw compared to meadow grass. The highest biomethane yield from wheat straw briquettes of 353 mL.g −1 VS was obtained with 6.27% (w/w) potassium hydroxide injection, which was 14% higher than from untreated wheat straw. The hydrolysis rates of wheat straw and meadow grass increased from 4.27 × 10 −2 to 5.32 × 10 −2  d −1 and 4.19 × 10 −2 to 6.00 × 10 −2  d −1 , respectively. The low water usage and no wastewater production make this a promising technology.